This invention relates to a circuit arrangement suitable for igniting a high-pressure discharge lamp and provided with
input terminals for connection to a voltage source; PA1 a pulse generating circuit provided with a switch, a primary winding of a pulse transformer, and capacitive means, which capacitive means shunt the switch and the primary winding; and PA1 an electrical connection between a secondary winding of the pulse transformer and lamp connection terminals.
A circuit arrangement of the kind mentioned in the opening paragraph is known from WO-A-95/28068. The known circuit arrangement is suitable for igniting a high-pressure discharge lamp which has a very high ignition voltage. Ignition pulses of a sufficient width and with an amplitude of up to 25 kV can be realized by means of the known circuit arrangement. It is required for an optimum operation of the known circuit arrangement, however, that two resonant circuits should be mutually attuned. The pulse generating circuit acts as the first resonant circuit. The second resonant circuit is the circuit formed by the secondary winding of the pulse transformer and the lamp connected to the lamp connection terminals. It is indeed possible to form high ignition voltage pulses in this manner, but it is a disadvantage that a slight mutual detuning of the resonant circuits already strongly reduces the maximum level of the generated voltage pulse. A further disadvantage is that the phase angle between the voltages generated in each resonant circuit will not necessarily be an integer number of times 180.degree., also in the case of an optimum mutual attuning. This again leads to a limitation in the level of the voltage pulse which can be generated.
Although it is also possible to ignite the lamp some time after it has extinguished, but has not yet cooled down, by means of the known circuit arrangement, a reliable instantaneous hot re-ignition is found to be substantially not possible.
It is an object of the invention to provide a circuit arrangement of the kind mentioned in the opening paragraph in which the above disadvantages are counteracted to a considerable extent.